Medical image diagnostic techniques using X-ray diagnostic apparatuses, MRI apparatuses, X-ray CT apparatuses, and the like have rapidly advanced with improvements in computer technology, and have become indispensable to current medical care.
Recently, X-ray diagnosis has advanced mainly in the field of circulatory organs with improvements in catheter techniques. An X-ray diagnostic apparatus for the diagnosis of circulatory organs generally includes an X-ray generation unit, an X-ray detection unit, a holding apparatus which holds the X-ray generation unit and the X-ray detection unit, a bed (top), a signal processing unit, and a display unit. The holding apparatus allows X-ray imaging at an optimal position or in an optimal direction by causing a C-arm or Ω arm pivot, rotate, or move around a patient (to be referred to as an object hereinafter).
The X-ray generation unit and the X-ray detection unit are mounted on the two ends of the C-arm in an arch shape so as to face each other. In order to prevent unnecessary exposure to X-rays and obtain accurate images, it is necessary in advance to match the X-ray center with the detector center. For this purpose, it is necessary to prevent positional shifts caused by the flexure of the C-arm by increasing its rigidity and ensuring the strength. However, with current needs for smaller, lighter apparatuses, it has become difficult to maintain necessary rigidity.
Recently, there have been increasing needs for smaller, lighter X-ray diagnostic apparatuses. In addition, there is a demand for reducing the thickness of the C-arm to decrease its height in the vertical direction while it is set in a vertical position. The thickness in this case indicates the length between the front surface (facing toward the isocenter) of the C-arm and the rear surface (located on the opposite side to the front surface). Further reducing the thickness can further reduce the total size of the apparatus including the C-arm.
In order to meet such needs, various studies have been made on materials for C-arms and their dimensions. Existing C-arms are aluminum extrudates or integrated products each made of a single material, manufactured by bending and welding a steel material. Owing to the physical property values of these members, it has become difficult to ensure necessary rigidity and strength.